Compressed gas cooling apparatus

ABSTRACT

A compressed gas cooling apparatus in which gas from an upstream compression stage enters an inlet section from an inlet opening and flows to a heat exchanger that cools the gas. The cooled gas then flows from the heat exchanger to the outlet section where the gas is discharged from an outlet opening. Pressure drop within the apparatus is decreased by providing the inlet and outlet sections with ever increasing and decreasing cross-sectional flow areas. In order to further decrease pressure drop due to a swirl within the gas flow imparted from the upstream compression stage, the inlet section is provided with first and second subsections wherein the cross-sectional flow area of the first subsection increases at lesser rate than the second subjection. Alternatively, or in addition, the inlet section can be provided with partitions to divide the gas flow into subflows in order to lessen pressure drop from swirl.

FIELD OF THE INVENTION

The present invention provides a compressed gas cooling apparatus thatcan function as an intercooler or an after-cooler and that is used tocool a gas between or after a series of compression stages. Moreparticularly, the present invention relates to such a cooling apparatusin which both the inlet and outlet have sections of ever-increasing andever-decreasing area, respectively, to feed gas to and from a heatexchanger positioned between the inlet and the outlet. Even moreparticularly, the present invention relates to such a cooling apparatusin which the ever-increasing section of the inlet is designed to furtherreduce pressure losses that occur due to the swirl in the gas flowimparted by the upstream compression stage introducing compressed gasinto the cooling apparatus.

BACKGROUND OF THE INVENTION

Large volumes of gas are compressed in a variety of industrialapplications within compression systems having a series of stages withintercooling between stages to cool the gas. The energy imparted to thegas in each of the compression stages heats the gas, also known as theheat of compression, is removed by the intercoolers. An after-cooler canbe positioned after the last of the compression stages.

Typically, each of the compression stages is formed by a centrifugalcompressor in which gas is drawn from an inlet to a vaned impeller thatis driven to accelerate the gas and thereby increase the pressure andvelocity of the gas. The pressure loss accompanying the increase invelocity is recovered in a diffuser that surrounds the impeller and thatcan have vanes. The gas is discharged from the impeller to a spiral-likevolute having an outlet from which the pressurized gas is discharged andthat surrounds the inlet. The intercooler is positioned between theoutlet of the upstream stage and the inlet of the downstream stage.Where the gas, such as air, contains moisture, the decrease intemperature of the compressed gas through intercooling and after-coolingresults in the condensation of such moisture which is discharged fromthe intercoolers and after-coolers so that the condensate is not carriedto downstream stages or to equipment conducting processes that consumethe compressed gas.

In air separation plants, the use of centrifugal compressors withintercoolers and after coolers is quite common. The compressors can bedriven by a transmission in which an electric motor drives a bull gearthat drives pinion-like gears that are attached to each of thecompressors to in turn drive the impellers. Thus, the compressors arearranged about the bull gear with piping having bends to route the gasto and from intercoolers located between the compressors. As known inthe art, the bends in such piping will induce a pressure drop within gaspassing between the compressors. Intercoolers are typically of shell andtube construction in which the tubes are used to pass a coolant, thatcan be water, into indirect heat exchange with the gas passing at rightangles to the tubes. Passages for the gas are formed by an arrangementof fins through which the tubes penetrate. The gas enters the shell ofsuch a heat exchanger through an inlet plenum and is discharged, at theopposite end of the shell from an outlet plenum. Gas is introduced anddischarged from such plenums at right angles to the shell through andinlet and outlet thereof. As can be appreciated there exists a furtherpressure loss from such arrangement due to the change in direction offlow and also, the rapid increase in cross-sectional flow area from theinlet to the inlet plenum and then from the outlet plenum to the outlet.In air separation plants, these pressure losses must be compensated forby increased compression and therefore, increased power consumption. Thesame considerations apply to other industrial application of multi-stagecompression systems.

Considerably more freedom in the placement of compressors andintercoolers is possible where the compressors are independently anddirectly driven by high speed permanent magnet motors. The freedom inthe placement of the compressors can be used to reduce pressure dropsthat accompany the intercooling and after-cooling of gases withinmulti-stage compression systems. For instance, in US Patent PublicationNo. 2010/0329895, the centrifugal compressors are independently drivenand are positioned so that the inlet of a downstream compressor islocated opposite to the outlet of an upstream compressor. Additionally,each of the inlets and outlets to the intercoolers have sections ofever-increasing transverse cross-sectional area and ever-decreasingtransverse cross-sectional area, respectively, with the heat exchangerspositioned between such sections. These sections can be formed by setsof four plates connected together in an arrangement of a four-sidepolyhedron and as such have a rectangular transverse cross-sectionalflow area. The heat exchangers that incorporate a box-like housing arelocated between these sections and internally, the heat exchangers havegas passages for the flow of the gas directly from and to such inlet andoutlet sections. The coolant passes through coolant passages at rightangles to the gas passages. As can be appreciated, such an arrangementreduces pressure losses that would otherwise arise from prior artarrangements having piping bends between stages and pressure losses dueto rapid changes of area and direction of flow to and from the heatexchanger and within the heat exchanger itself.

What has not been appreciated, even in the publication discussed above,is that pressure losses also arise from the swirl induced into the flowentering inlet and outlet sections of the intercooler or othercompressed gas cooling apparatus used in connection with a compressor.When the centrifugal compressor compresses the gas such a swirl in theflow is induced by the impeller and diffuser arrangement. When such flowenters an inlet to the intercooler or after-cooler, even one having agradually increasing cross-sectional flow area, the gas tends toaccumulate on the walls and at one side of the inlet. This creates ahigh pressure area where the flow accumulates and a low pressure areaadjacent the high pressure area. This causes separation of the flow fromthe walls and a recirculation within the inlet to the intercooler orafter-cooler that in turn produces a yet further component of theoverall pressure drop.

As will be discussed, the present invention, among other aspects,provides a compressed gas cooling apparatus that can function as anintercooler or an after-cooler that is designed to minimize pressuredrops within the inlet to the compressed gas cooling apparatus thatarise from the swirl imparted into the gas flow by the compressor.

SUMMARY OF THE INVENTION

The present invention provides a compressed gas cooling apparatus havinguse as an intercooler or an after-cooler. The apparatus is provided withan inlet section and an outlet section. The inlet section has an inletto receive a gas from an upstream compression stage and the outletsection has an outlet to discharge the gas, after having been cooled toa downstream compression stage. A heat exchanger connects the inletsection to the outlet section and has gas passages communicating betweenthe inlet section and the outlet section for passage of the gas andcoolant passages positioned in a heat transfer relationship with the gaspassages for passage of a coolant to cool the gas passing through thegas passages through indirect heat exchange with a coolant. The inletsection portion comprises a first inlet portion and a second inletportion. The first inlet portion is located between the inlet and thesecond inlet portion and the second inlet portion located between thefirst inlet portion and the heat exchanger. Each of the first inletportion and the second inlet portion has an ever increasing transversecross-sectional flow area. The ever increasing transversecross-sectional flow area of the second inlet portion increasing at agreater rate than the first inlet portion so that the velocity of theflow of the gas gradually decreases as the gas flows through the inletsection to a lesser extent in the first inlet portion than the secondinlet portion. This inhibits separation of the flow of the gas fromsidewalls of each of the first inlet portion and the second inletportion, due to swirl imparted into the flow of the gas from theupstream compression stage to reduce pressure drop. The outlet sectioncomprises one outlet portion of ever-decreasing transversecross-sectional flow area for flow of the gas from the heat exchanger tothe outlet such that velocity of the flow of the gas gradually increasesto also reduce pressure drop.

The first inlet portion, the second inlet portion and the one outletportion can be formed by sets of four sidewalls connected to one anothersuch that the ever-increasing transverse cross-sectional flow area andthe ever-decreasing transverse cross-sectional flow area are ofrectangular configuration. The heat exchanger has an inlet side and anoutlet side located opposite to the inlet side. The cooling passagesextend between the inlet side and the outlet side and each of the inletside and the outlet side is of rectangular configuration. The inletsection has a third inlet portion having a first transitional transversecross-sectional flow area that transitions from a circle, at one end, todefine the inlet and at the other end, a rectangle. The other end of thethird portion in registry with and connected to one of the sets of foursidewalls forming the first part of inlet portion. The one outletportion is a first outlet portion and the outlet section has a secondoutlet portion situated such that the first outlet portion is locatedbetween the second outlet portion and the heat exchanger. The secondoutlet portion has a second transitional transverse cross-section flowarea transitioning from a circle, at one end, to define the outlet andat the other end, a rectangle. The other end of the second outletportion is in registry with and connected to a further of the sets offour sidewalls forming the first outlet portion.

In a specific embodiment, another of the sets of four sidewalls formingthe second inlet portion, at opposite ends, is in registry with andconnected to the one of the sets of four sidewalls and the inlet side ofthe heat exchanger. The further of the sets of four sidewalls formingthe first outlet portion, at opposite ends, is in registry with andconnected to the other end of the second outlet portion and the outletside of the heat exchanger.

In order to further reduce the pressure drop resulting from swirl withinthe gas flow, the first inlet portion can be subdivided into a first setof subpassages by a first set of partition elements oriented such thateach of the subpassages is of rectangular configuration. The secondinlet portion can be subdivided into a second set of subpassages by asecond set of partition elements oriented such that each of thesubpassages is of rectangular configuration. The second set ofsubpassages have more subpassages than the first set of subpassages. Thefirst outlet portion can likewise be subdivided into a third set ofsubpassages by a third set of partition elements. The first set ofpartition elements, the second set of partition elements and the thirdset of partition elements are connected to the sidewalls andrectangular, frame-like stiffening members are connected to outersurfaces of each of the sets of the four sidewalls. In a specificembodiment, the first set of subpassages has four subpassages and thesecond set of subpassages has twenty-four subpassages.

An embodiment of the present invention also provides a compressed gascooling apparatus in which the inlet section comprises one portionhaving at least one sidewall forming an ever-increasing transversecross-sectional flow area. Partition elements subdivide theever-increasing transverse cross-sectional flow area into a plurality ofsubpassages, each having ever-increasing transverse cross-sectionalsub-flow areas so that velocity of the flow of the gas graduallydecreases as the gas flows through the inlet section. The sub-flow areasreduce separation of the flow of the gas from the at least one sidewall,due to swirl imparted into the flow of the gas from the upstreamcompression stage, thereby reducing pressure drop. The outlet sectioncomprises an outlet portion of ever-decreasing transversecross-sectional flow area for flow of the gas from the heat exchanger tothe outlet so that the velocity of the flow of the gas graduallyincreases as the gas flows in the outlet section to also reduce pressuredrop.

In such embodiment, the inlet portion and the outlet portion are formedby sets of four sidewalls connected to one another such that theever-increasing transverse cross-sectional flow area and theever-decreasing transverse cross-sectional flow area are of rectangularconfiguration. The subpassages are each of rectangular configuration.The heat exchanger has an inlet side, an outlet side located opposite tothe inlet side, the cooling passages that extend between the inlet sideand the outlet side. Each of the inlet side and the outlet side is ofrectangular configuration. The at least one sidewall of the inletportion is one of the sets of four sidewalls. A further of the sets offour sidewalls form the outlet portion. The inlet portion is a firstinlet portion and the outlet portion is a first outlet portion. Theinlet section has a second inlet portion and the outlet section has asecond outlet portion. The second inlet portion has a first transitionaltransverse cross-sectional flow area transitioning from a circle, at oneend, to define the inlet and at the other end, a rectangle. The otherend of the second inlet portion in registry with the one of the sets offour sidewalls forming the first inlet portion. Similarly, the secondoutlet portion has a second transitional transverse cross-section flowarea transitioning from a circle, at one end, to define the outlet andat the other end, a rectangle. The other end of the second outletportion is in registry with the further of the sets of four sidewalls.

The one of the sets of four sidewalls forming the first inlet portion isconnected to and in registry with the inlet side of the heat exchangerat a location of the inlet section opposite to the second inlet portion.The further of the sets of four sidewalls forming the first outletportion is connected to and in registry with the outlet side of the heatexchanger at a location of the outlet section opposite to the secondoutlet portion. The partition elements of the first inlet portion can bea first set of partition elements and the subpassages are a first set ofsubpassages and the first outlet portion has a second set of partitionelements that form a third set of subpassages of rectangularconfiguration. The first set of partition elements and the second set ofpartition elements are connected to the sidewalls. Rectangular,frame-like stiffening members are connected to outer surfaces of each ofthe sets of the four sidewalls.

In any embodiment of the present invention, the heat exchanger can be ofcross-counter flow arrangement. The cooling passages are formed betweena plurality of parallel fins oriented at right angles with respect tothe inlet side and the outlet side of the heat exchanger. The coolantpassages are formed by coolant tubes that penetrate the parallel finsfor circulation of the coolant and are in an orthogonal orientation withrespect to the parallel fins.

Preferably, the coolant tubes comprise a set of inlet coolant tubes, afirst set of intermediate coolant tubes, a second set of intermediatecoolant tubes and a set of outlet coolant tubes. These inlet,intermediate and outlet coolant tubes are arranged to provide fourpasses within the heat exchanger. The heat exchanger has two endportions located opposite to one another and two spaced, transverselyextending top and bottom panels connecting the end portions and formingthe inlet side and the outlet side of the heat exchanger. An inletplenum and an outlet plenum are situated, side by side, at one of thetwo end portions and are in flow communication with the inlet coolanttubes and the outlet coolant tubes, respectively, to introduce thecoolant into the inlet coolant tubes and to discharge the coolant fromthe outlet coolant tubes. Reversal plenums are located at the endportions of the heat exchanger and are configured such that coolant fromthe inlet tubes flows into the first set of intermediate coolant tubesat the other of the end portions, after having traversed the heatexchanger. The coolant then flows from the first set of intermediatecoolant tubes flows into the second set of intermediate coolant tubes atthe one of the end portions, after having traversed the heat exchanger.Subsequently, coolant from the second set of intermediate coolant tubesflows into the set of outlet coolant tubes, after having traversed theheat exchanger and thereafter, flows from the set of outlet coolanttubes into the outlet plenum.

The heat exchanger can have a condensate disengagement chamber locatedbetween the outlet side and the coolant tubes and the parallel fins toallow condensed water to separate from the compressed gas passingthrough the heat exchanger. An elongated, tube-like drain is located atthe bottom of the condensate disengagement chamber to collect thecondensed water separated from the gas and to discharge the condensedwater from the heat exchanger.

Further, within the heat exchanger, the coolant tubes can be connectedto and supported at their ends by two opposed tube sheets.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims distinctly pointing outthe subject matter that Applicants regard as their invention, it isbelieved that the invention will be better understood when taken inconnection with the accompanying drawings in which:

FIG. 1 is a perspective view of a compressed gas cooling apparatus ofthe present invention;

FIG. 2 is an exploded, perspective view of an inlet section used in theapparatus illustrated in FIG. 1;

FIG. 3 is a sectional, perspective view of the inlet section used in theapparatus illustrated in FIG. 1 taken along line 3-3 of FIG. 1;

FIG. 4 is a perspective view of an alternative embodiment of acompressed gas cooling apparatus of the present invention;

FIG. 5 is an exploded, perspective view of an inlet section used in theapparatus illustrated in FIG. 4.

FIG. 6 is a sectional perspective view of the inlet section used in theapparatus illustrated in FIG. 1 taken along line 6-6 of FIG. 4;

FIG. 7 is an exploded, perspective view of an outlet section used in theapparatus illustrated in FIGS. 1 and 4;

FIG. 8 is a top plan view of a heat exchanger in accordance with thepresent invention that is used in the apparatus illustrated in FIGS. 1and 4;

FIG. 9 is a fragmentary, sectional perspective view of the heatexchanger illustrated in FIG. 8 taken along line 9-9 thereof, showingfins, cooling passages and coolant tubes used within the heat exchanger;and

FIG. 10 is a sectional, perspective view of the heat exchanger used inthe apparatus illustrated in FIGS. 1 and 4 with the fins removed toillustrate the coolant tubes, inlet, outlet and reversal plenums and acondensate disengagement chamber and drain thereof.

DETAILED DESCRIPTION

With reference to FIG. 1, a compressed gas cooling apparatus 1 inaccordance with the present invention is illustrated. As mentionedabove, such apparatus can function as an intercooler between compressionstages or an after-cooler to cool the gas discharged from a compressionstage to be used in downstream processing. Apparatus 1 has an inletsection 2, an outlet section 3 and a heat exchanger 4 connecting theinlet section 2 to the outlet section 3. The inlet section 2 has aninlet 10 to receive a gas flow “A” from an upstream compression stage,not illustrated. The upstream compression stage could be a centrifugalcompressor or an axial compressor. In either case, the gas flowindicated by arrowhead “A” entering the inlet 10 has a swirl or arotational component to the flow designated by curved arrowhead “B”.Such swirl is imparted to the flow by the rotational components of thecompressor, for instance, the impeller of a centrifugal compressor.

The gas flow “A”, after having been cooled in the heat exchanger 4 isdischarged from an outlet 12 of the outlet section 3 as a cooled gasflow shown as arrowhead “C”.

With additional reference to FIGS. 2 and 3, inlet section 2 is providedwith a first inlet portion 14, a second inlet portion 16 and optionally,a third inlet portion 18. As is apparent, all of these portions have anever increasing transverse cross-sectional flow area that will act togradually reduce the velocity of the gas flow before entering the heatexchanger 4. This will reduce pressure drop or loss in the flow due toturbulence that would otherwise be induced in the gas flow due to asudden enlargement in cross-sectional flow area from the inlet opening10. However, the pressure drop or loss in the gas flow also arises fromthe swirl “B” introduced into the flow by the upstream compressor. This“swirl” or rotation in the flow tends to cause the gas to accumulate onone side of the inlet section 2. This accumulation in turn creates ahigh pressure area and an adjacent low pressure area. As a result, aseparation of the gas flow appears at wall regions of the inlet portiontowards the adjacent low pressure region which in turn results in abackward circulation of the gas flow leading to an increase in pressuredrop in the gas flow.

The first inlet portion 14 is formed by a set of four sidewalls 20, 22,24 and 26 that are connected to one another such that theever-increasing transverse cross-section flow area is of rectangularconfiguration. The second inlet portion 16 is formed by another set offour sidewalls 28, 30, 32 and 34 that are connected to one another toagain form an ever-increasing transverse cross-sectional flow are ofrectangular configuration. Specifically, the swirl “B” will tend tocause the gas flow “A” to accumulate along sidewalls 26 and 34 of thefirst and second sections 14 and 16 and portions of adjacent sidewalls20, 24 and 28,32 located close to the sidewalls 26 and 34. This willcreate a high pressure field within the gas flow “A” at such sidewallregions. In more central regions of the first and second sections 14 and16, located at a distance from the sidewalls 26 and 34, the flow is notsubject to such accumulation and therefore, has a lower pressure. Asmentioned above, this pressure difference will potentially causerecirculation of the gas flow “A” from the higher to the lower pressureregions resulting in a pressure drop.

However, as can best be seen in FIG. 3, the ever-increasing transversecross sectional flow area of the second inlet portion 16 increases at agreater rate than that of the first inlet portion 14. The effect of thisis that the velocity of the gas flow through the first inlet portion 14will decrease to a lesser extent than the gas flow within the secondinlet portion 16. The resulting higher velocity of the gas flow withinthe first inlet portion 14 will tend to reduce the separation of the gasflow from the walls of the inlet section 2 and allow the swirl “B” todissipate somewhat before the gas flow reaches the second inlet portion16. Since flow velocity is also decreasing along the length of thesecond inlet portion 16, pressure drop in the gas flow that otherwisewould have been produced by the swirl “B” and a sudden increase in areawill be reduced. The second inlet portion abuts the heat exchanger 4 andthereby also serves to distribute the gas flow across the heat exchanger4.

In order to best reduce the pressure drop resulting from the swirl “B”,the first and second sections 14 and 16 are preferably designed to lietangent to a bell-shaped curve given by the formula for an ellipse(bell-shape) ((x−i)²/a²)+((y−j)²/b²)=1 where (i, j) is the centre of theellipse, a and b are the half distances on x and y axes respectively.First section 14 would originate from the apex of such bell shape andsecond section 16 would terminate at the mount of such bell shape. Evenmore preferably, first section 14 has an aspect ratio of between 0.4 and0.5. This aspect ratio is measured by dividing the maximum width offirst section 14, as seen at the juncture of the first section 14 withthe second section 16, by its length. The second section 16 preferablyhas an aspect ratio of between 0.2 and 0.4. This aspect ratio ismeasured by dividing the maximum width of second section 16, as seen atthe juncture of the second section 16 with the heat exchanger 4, by itslength.

While the first and second inlet portions 14 and 16 alone will tend toreduce pressure drop in the gas flow for reasons mentioned above,preferably, the rectangular cross-sectional flow areas of the firstinlet portion 14 is divided into a first set of subpassages, for examplesubpassage 36 and the second inlet portion 16 is subdivided into asecond set of subpassages, for example subpassage 38. These rectangularsubdivisions serve to reduce pressure drop further by preventing gasflow from accumulating on one side of the inlet portion 2 as a result ofthe swirl “B”. The first set of subpassages 36 are formed by a first setof partition elements 40 and 42, positioned at right angles to oneanother and the second set of subpassages 38 are formed from sets ofpartition elements 40 and 42 and 44 and 46. Partition elements 40 and 42extend the length of the first inlet portion 14 and the second inletportion 16. Partition elements 44 and 46 are confined to the secondinlet portion 16 and are positioned at right angles to one another. Asillustrated each of the subpassages 36 and 38 are of rectangularconfiguration and are each of ever increasing area.

The partition element 40 is connected along its edges to sidewalls 20,24 and 28, 32; and the partition element 42 is connected along its edgesto sidewalls 22, 26; and 30, 34. Further, the partition elements 44 areconnected to sidewalls 28 and 32 and the partition elements 46 areconnected to sidewalls 30 and 34. These connections are preferred inorder to help maintain structural integrity of the first inlet portion14 and the second inlet portion 16 and are normally in tension duringuse of the apparatus 1. Further structural integrity is provided byframe-like stiffing members 48 connected to the set of sidewalls 20, 22,24 and 26 forming the first inlet portion 14 and to sidewalls 28, 30, 32and 34 forming the second inlet portion 16. As can be appreciated, suchconnections of the partition elements and the use of the frame-likestiffing members to reduce the thickness and weight of the sidewalls 20through 34 that are necessary to contain compressed gases at highpressure.

As illustrated, the second inlet portion 16 has more subpassages 38 thanthe subpassages 36 of the first inlet portion 14. Preferably there are24 of such subpassages 38 as compared with the four subpassages 36. Amajor reason for this is that since the first inlet portion 14 has asmaller cross-section than the second inlet portion 16, there is lessstress and therefore, fewer partition elements are required in the firstinlet portion for structural integrity.

Although first inlet section 14 could simply be provided with a circularopening to form the inlet 10, preferably, the third inlet portion 18 isprovided having a transitional transverse, cross-sectional flow areathat transitions from the circular inlet opening 10, at one end and arectangle at the other end. The sidewalls 50 thereof are therefore,curved at the inlet opening 10 and are planar at the other end thereofto form the rectangle. This again helps to lower pressure drop byavoiding an abrupt transition between the circular inlet opening 10 andthe rectangular cross-sectional flow areas provided by the first inletportion 14 and the second inlet portion 16.

Preferably, the sidewalls 50 are connected to and in registry with thesidewalls 20, 22, 24 and 26 of the first inlet portion 14. The sidewalls20, 22, 24 and 26 are also preferably connected to an in registry withthe sidewalls 28, 30, 32 and 34 of the second inlet portion 16. Thesidewalls 28, 30, 32 and 34 are connected to and in registry with theinlet side 106 of the heat exchanger 4. It is possible, however toprovide a spacer section having a uniform, rectangular cross-sectionalflow area between the second inlet section 16 and the heat exchanger 4.Likewise it is also possible to provide such a spacer section betweeneither or both of the first inlet section 14 and the second inletsection 16 or between the third inlet portion 18 and the first inletportion 14.

With reference to FIGS. 4 and 5, a compressed gas cooling apparatus 1′is illustrated that is an alternative embodiment of the apparatus 1.Apparatus 1′ differs from apparatus 1 in that it is provided with aninlet section 2′ having a first inlet portion 52 of ever increasingcross-sectional flow area and a second inlet portion 54 of similarconfiguration to the third inlet portion 18 of apparatus 1.

First inlet portion 52 is formed by a set of four sidewalls 56, 58, 60and 62 that are connected to one another such that the ever-increasingtransverse cross-section flow area is of rectangular configuration.Again, although a simple inlet opening could be provided, the secondinlet portion 54 provided further pressure drop by provision of itstransitional transverse cross-section flow area that transitions fromthe circular inlet opening 10′, at one end and a rectangle at the otherend. The sidewalls 64 thereof are therefore, curved at the inlet opening10′ and are planar at the other end thereof to form the rectangle. Thesidewalls 64, at the other end of second inlet portion 54 are connectedto an in registry with sidewalls 56, 58, 60 and 62 of the first inletportion 56.

With additional reference to FIG. 6, pressure drop within the inletsection 2′ is reduced by provision of the ever-increasing transversecross-section flow area provided by the first inlet portion 52. Thepressure drop due to swirl is reduced by means of a set of partitions 66and 68, positioned at right angles with respect to one another and thatsubdivide the transverse cross-sectional flow area into subpassages, forinstance subpassage 70, each of ever increasing transverse crosssectional flow area. The partition elements 66 and 68 prevent theformation of a high pressure wall region, resulting from the swirl inthe flow, from influencing the subflows in adjacent subpassages 70.

The partitions 66 and 68 are also connected to the sidewalls 56, 60 and58, 62, respectively, to add to the structural integrity of the firstportion 52 of the inlet section 2′. Additionally, optional frame-likestiffening members 72 connected to the outer surfaces of the sidewalls56, 58, 60 and 62 add to the structural integrity and strength of thefirst portion 52.

With additional reference to FIG. 7, outlet section 3 again has an everdecreasing transverse cross-section flow area to allow the velocity ofthe flow to gradually increase. The design of the outlet section 3 isless critical in decreasing pressure drop than the inlet sections 2 and2′ of the apparatus 1 and 1′, respectively. In fact, the illustratedoutlet section 3 is of the same design in both apparatus 1 and 1′.Alternatively, the outlet section 3 could have the same design as eitherof the inlet sections 2 and 2′.

The illustrated outlet section 3 is preferably provided with a firstoutlet portion 74 and a second outlet portion 76. The first outletportion 74 is formed by a set of four sidewalls 78, 80, 82 and 84connected together to provide a rectangular, transverse cross-sectionflow area. Although the first outlet portion 74 could terminate in anoutlet opening, preferably, to reduce pressure drop, the second outletportion 76 has a second transitional transverse cross-section flow areaformed by a set of four sidewalls 86, 88, 90 and 92 that transitionsfrom a circle, at one end, to define an outlet 94 from which the outletstream “C” is discharged and at the other end, a rectangle. Sidewalls86, 88, 90 and 92 are connected to and in registry with the foursidewalls 78, 80, 82 and 84 forming the first outlet portions 74.

Preferably, for purposes of structural integrity, sets of partitions 96and 98 are provided that are connected to sidewalls 80, 84 and sidewalls78, 82, respectively. Additionally, rectangular frame-like members 100can be connected to the sidewalls 78, 80, 82 and 84 to provideadditional strength.

With additional reference to FIG. 8, heat exchanger 4 is of commondesign with respect to apparatus 1 and apparatus 1′ and functions toremove the heat of compression from the incoming gas stream “A” byproviding indirect heat exchange between a cooling fluid and the gasstream. The cooling fluid, which can be water, enters through an inlet102 and is discharged from an outlet 104. As illustrated in FIG. 1, heatexchanger 4 connects the inlet section 2 to the outlet section 3 withrespect to apparatus 1. Similarly, heat exchanger 4 also connects inletsection 2′ to outlet section 3 in apparatus 1′. Heat exchanger 4 isprovided with an inlet side 106 connected to inlet sections 2 and 2′ andan outlet side 108 connected to outlet section 3. As mentioned above,the connections need not be direct and rectangular spacer-like elementscould be provided within such sections. The gas to be cooled enters theheat exchanger 4 from the inlet sections 2 and 2′at the inlet side 106and the cooled gas is discharge from the heat exchanger 4 from theoutlet side 108 to the outlet section 3.

As can best be seen in FIG. 9, the indirect heat exchange within heatexchanger 4 is accomplished by means gas passages 110 that are formedbetween a series of parallel, fin-like plate elements 112. The fin-likeplate elements 112 are penetrated by a set of outlet coolant tubes 122which provide the coolant passages for the coolant. Although notillustrated, the fin-like plate elements 112 are also penetrated byother sets of coolant tubes designated by reference numbers 116, 118 and120 and to be discussed hereinafter. In this regard, inlet side 106 isan open rectangular area that is framed to receive the gas flow “A” andpass into the gas passages 110. Similarly, the outlet side 108 is anopen rectangular area that is framed to discharge the gas flow “A”,after having been cooled, to the outlet section 3. In the illustratedapparatus 1 and 1′, the rectangular areas are equal to those provided byinlet section 2 and 2′ and outlet section 3.

With additional reference to FIG. 10, the coolant tubes comprise a setof inlet coolant tubes 116, first and second sets of intermediatecoolant tubes 118 and 120 and a set of outlet coolant tubes 122. Theaforementioned coolant tubes are supported at opposite ends byperforated tube sheets 124 and 126 and at intermediate locations by thefin-like plate elements 112. Optional support plates 128 are connectedat opposite ends to transversely extending top and bottom panels 134 and136 to assist in maintaining structural integrity against internalpressures. It is to be noted that the heat exchanger 4 has two endportions 130 and 132 located opposite to one another that are connectedthe two spaced, transversely extending top and bottom panels 134 and 136thereby forming the inlet side 106 and the outlet side 108 of the heatexchanger which are rectangular openings to the heat exchanger by virtueof such construction. A base 138 is connected to the bottom panel 136 toelevate the bottom panel 132 above ground level.

Contained within end portion 130 is an inlet plenum 140 and an outletplenum 142 that are located side-by-side, are situated within endportion 130. Inlet plenum 140 and outlet plenum 142 are in flowcommunication with the inlet coolant tubes 116 and the outlet coolanttubes 122, respectively. The coolant is introduced into the inletcoolant tubes 116 from the inlet 102 in direction of the arrowhead “D”and is discharged from the outlet coolant tubes through the outletplenum 142 and to the outlet 104 in direction of arrowhead “E”. Areversal plenum 144 is located between the inlet plenum 140 and theoutlet plenum 142 and two reversal plenums 146 and 148 are formed withinthe other end portion 132 by provision of a dividing plate 150. Thecoolant enters the inlet tubes 116 from the inlet plenum 140. Aftertraversal of the heat exchanger, the coolant reverses flow directionwithin reversal plenum 146 in the direction of arrowhead “G” and thenflows through the first set of intermediate coolant tubes 118 until thecoolant reaches the reversal plenum 144. Within reversal plenum 144, thecoolant again reverses direction and flows through the second set ofintermediate coolant tubes 120 until reaching reversal plenum 148. Atreversal plenum 148, the coolant again reverses direction in thedirection of arrowhead “H” and flows through the outlet coolant tubes122 to the outlet plenum 142 from which the coolant is discharged fromheat exchanger 4 from the outlet 104.

In case of such gases as air, the incoming air will contain water vaporthat will be condensed by the coolant. In order to disengage the water,a disengagement chamber 152 is provided adjacent to the outlet side 108of the heat exchanger 4. The disengaged water, collects in the bottompanel 136 and is discharged from openings 154 and 156 to an elongated,tube-like drain 158 located beneath the bottom panel 136 and adjacentthe base 138 for discharge of the collected water.

While the present invention has been described with reference topreferred embodiments, as will occur to those skilled in the art,numerous changes, additions and omissions can be made without departingfrom the spirit and scope of the present invention as set forth in theappended claims.

We claim:
 1. A compressed gas cooling apparatus comprising: an inletsection having an inlet to receive a gas from an upstream compressionstage; an outlet section having an outlet to discharge the gas, afterhaving been cooled to a downstream compression stage; a heat exchangerconnecting the inlet section to the outlet section and having gaspassages communicating between the inlet section and the outlet sectionfor passage of the gas and coolant passages positioned in a heattransfer relationship with the gas passages for passage of a coolant tocool the gas passing through the gas passages through indirect heatexchange with a coolant; the inlet section comprising a first inletportion and a second inlet portion, the first inlet portion locatedbetween the inlet and the second inlet portion and the second inletportion located between the first inlet portion and the heat exchanger;and each of the first inlet portion and the second inlet portion havingan ever increasing transverse cross-sectional flow area, the everincreasing transverse cross-sectional flow area of the second inletportion increasing at a greater rate than the first inlet portion sothat the velocity of the flow of the gas gradually decreases as the gasflows through the inlet section to a lesser extent in the first inletportion than the second inlet portion and separation of the flow of thegas from sidewalls of each of the first inlet portion and the secondinlet portion, due to swirl imparted into the flow of the gas from theupstream compression stage, is inhibited to reduce pressure drop; andthe outlet section comprising one outlet portion of ever-decreasingtransverse cross-sectional flow area for flow of the gas from the heatexchanger to the outlet such that velocity of the flow of the gasgradually increases to also reduce pressure drop.
 2. The apparatus ofclaim 1, wherein: the first inlet portion, the second inlet portion andthe one outlet portion are formed by sets of four sidewalls connected toone another such that the ever-increasing transverse cross-sectionalflow area and the ever-decreasing transverse cross-sectional flow areaare of rectangular configuration; the heat exchanger has an inlet side,an outlet side located opposite to the inlet side, the cooling passagesextend between the inlet side and the outlet side and each of the inletside and the outlet side is of rectangular configuration; the inletsection has a third inlet portion having a first transitional transversecross-sectional flow area transitioning from a circle, at one end, todefine the inlet and at the other end, a rectangle, the other end of thethird portion in registry with and connected to one of the sets of foursidewalls forming the first inlet portion; the one outlet portion is afirst outlet portion; the outlet section has a second outlet portionsituated such that the first outlet portion is located between thesecond outlet portion and the heat exchanger, the second outlet portionhaving a second transitional transverse cross-section flow areatransitioning from a circle, at one end, to define the outlet and at theother end, a rectangle; and the other end of the second outlet portionis in registry with and connected to a further of the sets of foursidewalls forming the first outlet portion.
 3. The apparatus of claim 2,wherein another of the sets of four sidewalls forming the second inletportion, at opposite ends, is in registry with and connected to the oneof the sets of four sidewalls and the inlet side of the heat exchanger;and the further of the sets of four sidewalls forming the first outletportion, at opposite ends, is in registry with and connected to theother end of the second outlet portion and the outlet side of the heatexchanger.
 4. The apparatus of claim 2, wherein: the first inlet portionis subdivided into a first set of subpassages by a first set ofpartition elements oriented such that each of the subpassages is ofrectangular configuration; the second inlet portion is subdivided into asecond set of subpassages by a second set of partition elements orientedsuch that each of the subpassages is of rectangular configuration; thesecond set of subpassages having more subpassages than the first set ofsubpassages.
 5. The apparatus of claim 4, wherein: the first outletportion is subdivided into a third set of subpassages by a third set ofpartition elements; the first set of partition elements, the second setof partition elements and the third set of partition elements areconnected to the sidewalls; and rectangular, frame-like stiffeningmembers are connected to outer surfaces of each of the sets of the foursidewalls.
 6. The apparatus of claim 4, wherein the first set ofsubpassages has four subpassages and the second set of subpassages hastwenty-four subpassages.
 7. A compressed gas cooling apparatuscomprising: an inlet section having an inlet to receive a gas from anupstream compression stage; an outlet section having an outlet todischarge the gas, after having been cooled to a downstream compressionstage; a heat exchanger connecting the inlet section to the outletsection and having gas passages communicating between the inlet sectionand the outlet section for passage of the gas and coolant passagespositioned in a heat transfer relationship with the gas passages forpassage of a coolant to cool the gas passing through the gas passagesthrough indirect heat exchange with a coolant; the inlet sectioncomprising one portion having at least one sidewall forming anever-increasing transverse cross-sectional flow area and partitionelements subdividing the ever-increasing transverse cross-sectional flowarea into a plurality of subpassages, each having ever-increasingtransverse cross-sectional sub-flow areas so that velocity of the flowof the gas gradually decreases as the gas flows through the inletsection and the sub-flow areas reduce separation of the flow of the gasfrom at least one sidewall, due to swirl imparted into the flow of thegas from the upstream compression stage, thereby reducing pressure drop;and the outlet section comprising an outlet portion of ever-decreasingtransverse cross-sectional flow area for flow of the gas from the heatexchanger to the outlet so that the velocity of the flow of the gasgradually increases as the gas flows in the outlet section to alsoreduce pressure drop.
 8. The apparatus of claim 7, wherein: the inletportion and the outlet portion are formed by sets of four sidewallsconnected to one another such that the ever-increasing transversecross-sectional flow area and the ever-decreasing transversecross-sectional flow area are of rectangular configuration; thesubpassages are each of rectangular configuration; the heat exchangerhas an inlet side, an outlet side located opposite to the inlet side,the cooling passages extend between the inlet side and the outlet sideand each of the inlet side and the outlet side is of rectangularconfiguration; the at least one sidewall of the inlet portion is one ofthe sets of four sidewalls; a further of the sets of four sidewalls formthe outlet portion; the inlet portion is a first inlet portion, theoutlet portion is a first outlet portion, the inlet section has a secondinlet portion and the outlet section has a second outlet portion; thesecond inlet portion has a first transitional transverse cross-sectionalflow area transitioning from a circle, at one end, to define the inletand at the other end, a rectangle, the other end of the first inletportion in registry with the one of the sets of four sidewalls formingthe first inlet portion; the second outlet portion has a secondtransitional transverse cross-section flow area transitioning from acircle, at one end, to define the outlet and at the other end, arectangle; and the other end of the second outlet portion is in registrywith the further of the sets of four sidewalls.
 9. The apparatus ofclaim 8, wherein: the one of the sets of four sidewalls forming thefirst inlet portion is connected to and in registry with the inlet sideof the heat exchanger at a location of the inlet section opposite to thesecond inlet portion; and the further of the sets of four sidewallsforming the first outlet portion is connected to and in registry withthe outlet side of the heat exchanger at a location of the outletsection opposite to the second outlet portion.
 10. The apparatus ofclaim 8 wherein: the partition elements of the first inlet portion are afirst set of partition elements and the subpassages are a first set ofsubpassages; the first outlet portion has a second set of partitionelements that form a third set of subpassages of rectangularconfiguration; the first set of partition elements and the second set ofpartition element are connected to the sidewalls; and rectangular,frame-like stiffening members are connected to outer surfaces of each ofthe sets of the four sidewalls.
 11. The apparatus of claim 2 or claim 4or claim 5 or claim 8 or claim 10, wherein: the heat exchanger is ofcross-counter flow arrangement; the cooling passages are formed betweena plurality of parallel fins oriented at right angles with respect tothe inlet side and the outlet side of the heat exchanger; and thecooling passages are formed by coolant tubes that penetrate the parallelfins for circulation of the coolant and are in an orthogonal orientationwith respect to the parallel fins.
 12. The apparatus of claim 11,wherein: the coolant tubes comprise a set of inlet coolant tubes a firstset of intermediate coolant tubes, a second set of intermediate coolanttubes and a set of outlet coolant tubes arranged to provide four passeswithin the heat exchanger; the heat exchanger has two end portionslocated opposite to one another and two spaced, transversely extendingtop and bottom panels connecting the end portions and forming the inletside and the outlet side of the heat exchanger; an inlet plenum and anoutlet plenum are located side-by-side, are situated at one of the twoend portions and are in flow communication with the inlet coolant tubesand the outlet coolant tubes, respectively, to introduce to the coolantinto the inlet coolant tubes and to discharge the coolant from theoutlet coolant tubes; and reversal plenums are located at the endportions of the heat exchanger and are configured such that coolant fromthe inlet tubes flows into the first set of intermediate coolant tubesat the other of the end portions, after having traversed the heatexchanger, coolant from the first set of intermediate coolant tubesflows into the second set of intermediate coolant tubes at the one ofthe end portions, after having traversed the heat exchanger, coolantfrom the second set of intermediate coolant tubes flows into the set ofoutlet coolant tubes, after having traversed the heat exchanger andthereafter, flows from the set of outlet coolant tubes into the outletplenum.
 13. The apparatus of claim 11, wherein the heat exchanger has acondensate disengagement chamber located between the outlet side and thecoolant tubes and the parallel fins to allow condensed water to separatefrom the compressed gas passing through the heat exchanger and anelongated, tube-like drain located at the bottom of the condensatedisengagement chamber to collect the condensed water separated from thegas and to discharge the condensed water from the heat exchanger. 14.The apparatus of claim 12, wherein the heat exchanger has a condensatedisengagement chamber located between the outlet side and the coolanttubes and the parallel fins to allow condensed water to separate fromthe compressed gas passing through the heat exchanger and an elongated,tube-like drain located at the bottom of the condensate disengagementchamber to collect the condensed water separated from the gas and todischarge the condensed water from the heat exchanger.
 15. The apparatusof claim 13, wherein the coolant tubes are connected to and supported attheir ends by two opposed tube sheets.